Add emptyOnZero option to display total:0 bars as empty, not full

[nickcmaynard]

... also add devDependencies so npm run test works.

[AndiDittrich]

Hi @nickcmaynard

i'll check this soon - there were a few reasons in the past to set the value to 1.0

[nickcmaynard]

Great stuff - thanks. This defaults to current behaviour, so I hope this should be fairly low impact.

[AndiDittrich]

in which cases does the unexpected behaviour appear ?
i can only reproduce the 1.0 fallback in case total is set to 0:

Example 1 - total=100

const b1 = new _progress.Bar();
b1.start(100, 0);

 $ node dev.js 
progress [----------------------------------------] 0% | ETA: 0s | 0/200

Example 1 - total=0

const b1 = new _progress.Bar();
b1.start(0, 0);

 $ node dev.js 
progress [========================================] 100% | ETA: 0s | 0/0

[nickcmaynard]

in which cases does the unexpected behaviour appear ?
i can only reproduce the 1.0 fallback in case total is set to 0:

Yes - precisely this case. My use case pre-initialises a number of progress bars - "stages" - but the size of those stages isn't known until later in the execution.

Now, I could pre-inititialise total to a non-zero value, but that would erroneously imply it's correct.

Thank you for merging :)

[AndiDittrich]

ok, i've never projected such use case